Author Topic: Cloning the HP3325A Option 002 - HV Output  (Read 6116 times)

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Offline Jay_Diddy_B

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Cloning the HP3325A Option 002 - HV Output
« on: April 07, 2019, 02:37:20 am »
Hi,
This thread is dedicated to cloning the high voltage option board A8 used in the HP3325A option 002 HV Output.

I have successfully cloned this board in the past, but I have lost the files.

Here are pictures of my clone:





I have attached the section from the manual.

I remember entering the schematic from the manual and then placing the components in the same place and orientation as the HP original. I used the net list as a guide as where to route the tracks.

I used MPS8099 (NPN) and MPS8599 (PNP) for all the small transistors. Q1 on the original is a dual transistor. I just used two MPS8099 glued together.

I used MJE243 (NPN) and MJE172 (PNP) for the output transistors.

Regards,

Jay_Diddy_B

« Last Edit: April 07, 2019, 02:41:54 am by Jay_Diddy_B »
 
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Re: Cloning the HP3325A Option 002 - HV Output
« Reply #1 on: April 07, 2019, 04:00:46 am »
I think I'll do a similar thing re. placing the components to replicate the HP layout, with maybe a few little alterations as I find along the way to neaten the routing etc.
I have been having a look at cross referencing of the silicon so far.


So far I have this (Subject to change):
(Part numbers from Digikey)
  • Dual NPN Transistor 1854-0475 (supersedes to 1854-1030 and 1854-0688) - MAT01GHZ + heatsink 323005B00000G
  • All PNP transistors - 2N3906
  • 15V Zener 1902-3205 - 1N5245
  • 30V Zener 1902-0244 - 1N4751
  • Switching Diode 30V 1901-0040 - 1N4148
  • Switching Diode 80V 1901-0050 - 1N4150


Other parts so far:
  • RCA Socket - RCJ-021
  • TO-220 Heatsink - V2109B
  • 3-Pin Connector - Molex KK5273 Series - 0009652038
  • Bridge Rectifier MDA202 - KPB204G


Jay_Diddy_B, what did you use for the board interconnects? I am looking for short pre-made 90o RCA cables but I haven't turned up anything with a quick search yet..
Also, what are the dimensions of your board?
« Last Edit: April 07, 2019, 04:27:31 am by TERRA Operative »
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Offline Jay_Diddy_B

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Re: Cloning the HP3325A Option 002 - HV Output
« Reply #2 on: April 07, 2019, 09:59:50 am »

Jay_Diddy_B, what did you use for the board interconnects? I am looking for short pre-made 90o RCA cables but I haven't turned up anything with a quick search yet..
Also, what are the dimensions of your board?

I measured the board that I made:



The holes are 0.250 inches in from the sides. The board is 4.600 x 2.350 inches. (too big for the 100mm x 100mm cheap boards  :( )

Regards,

Jay_Diddy_B
 
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Re: Cloning the HP3325A Option 002 - HV Output
« Reply #3 on: April 07, 2019, 12:40:25 pm »
Awesome, thanks.

Yeah, I thought it would be too big for the cheap boards.. :(
Ah well, it's still not tooooo expensive anyway. I wonder if there is anywhere that will do gold plating and also clear or no solder mask to match the old HP style PCB? :D
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Offline Jay_Diddy_B

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Re: Cloning the HP3325A Option 002 - HV Output
« Reply #4 on: April 07, 2019, 02:34:05 pm »
Hi,

I have put together an LTspice model for the amplifier. I have picked some transistors that I am familiar with in the LTspice library. This is the same as the original HP circuit. I haven't done any tweaks.











I haven't compared these results to the hardware.

I have attached the model.

Regards,
Jay_Diddy_B
« Last Edit: April 07, 2019, 02:38:38 pm by Jay_Diddy_B »
 
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Re: Cloning the HP3325A Option 002 - HV Output
« Reply #5 on: April 08, 2019, 02:27:44 am »
Nice work. I haven't used LTspice before, I should learn it some day..
Is there a spice model for the MAT01GHZ for the dual transistor? I wonder how much of a difference it would make.

Also, that square wave looks a bit nasty, how does it look on a scope from your physical unit?
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Offline Jay_Diddy_B

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Re: Cloning the HP3325A Option 002 - HV Output
« Reply #6 on: April 08, 2019, 03:37:05 am »
Hi,
I am not sure why the LTspice waveform is distorted.

I would not use the MAT01. It is not recommended for new designs (NRND). I think that it is because it is in a metal can.

The main property of the MAT01, matching is not needed in this high voltage amplifier. The voltage gain of the circuit is only 2.

I have good news!!  :D

I have an original option 002 that I was able to compare with my clone.

Original




Clone



Not a lot of difference.

Regards,

Jay_Diddy_B



« Last Edit: April 08, 2019, 04:29:28 am by Jay_Diddy_B »
 

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Re: Cloning the HP3325A Option 002 - HV Output
« Reply #7 on: April 08, 2019, 04:25:27 am »
Well, that's good news that the MAT01 isn't needed, that will certainly save a good few $$$ and make future builds easier too.

Can you post a few photos of the original HP option board? I want to see it all close up. :D
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Offline Jay_Diddy_B

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Re: Cloning the HP3325A Option 002 - HV Output
« Reply #8 on: April 08, 2019, 04:30:55 am »
Well, that's good news that the MAT01 isn't needed, that will certainly save a good few $$$ and make future builds easier too.

Can you post a few photos of the original HP option board? I want to see it all close up. :D


I will do tomorrow, it is very late here in Toronto.

Regards,

Jay_Diddy_B
 

Offline Jay_Diddy_B

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Re: Cloning the HP3325A Option 002 - HV Output
« Reply #9 on: April 08, 2019, 11:24:22 am »
Hi group,

I have taken some photographs of the original board.
The board is slightly smaller than the one I made. The dimensions are 4.500 x 2.25 Inches. The fixing holes are the same.

I did notice a few differences:

All the mounting holes are grounded on the original.
There are ferrite beads on the base leads of Q4 and Q5.


Here are the pictures:












Regards,
Jay_Diddy_B


 
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Re: Cloning the HP3325A Option 002 - HV Output
« Reply #10 on: April 10, 2019, 01:16:31 am »
I just finished drawing up the schematic in DipTrace.

Next step is to start laying out the PCB.

[Edit: Fixed schematic]
« Last Edit: May 31, 2019, 01:11:38 am by TERRA Operative »
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Offline Jay_Diddy_B

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Re: Cloning the HP3325A Option 002 - HV Output
« Reply #11 on: April 10, 2019, 02:43:41 am »
Hi,

I have had a quick look at the schematic.

1) R10 should be 3.6 \$\Omega\$

2) Q14 should be a NPN power transistor MJE182 or similar
HP used MJE223

3) Q15 should be a PNP power transistor MJE172 or similar
HP used MJE233

4) C9 should be 22uF 50V Electrolytic capacitor

5) Most of the small signal transistors need to be more than 40V



1853-0036 was selected from 2N3906 (probably for Vceo >60V)

1853-0042 is a 50V PNP transistor

1853-0020 is a 25V PNP transistor

I used MPS8099 and MPS8599 on the board I built.

Regards,

Jay_Diddy_B
« Last Edit: April 10, 2019, 02:50:22 am by Jay_Diddy_B »
 

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Re: Cloning the HP3325A Option 002 - HV Output
« Reply #12 on: April 10, 2019, 03:52:59 am »
That'll teach me for doing it at 3am...

I'll make a revision tonight, maybe before midnight this time. :D
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Re: Cloning the HP3325A Option 002 - HV Output
« Reply #13 on: April 10, 2019, 12:24:08 pm »
Ok, I fixed up the schematic and reuploaded it in my post above, except I still am looking at easy to source transistors.
The MJE243 and MJE172 are easy, but Digikey doesn't have MPS8099 and MPS8599 as they are marked as obsolete, Mouser has them though, so it should be ok.

I wonder if the KSC945 (NPN) and KSA733 (PNP) would be ok substitutes?
« Last Edit: April 10, 2019, 12:37:46 pm by TERRA Operative »
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Offline vindoline

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Re: Cloning the HP3325A Option 002 - HV Output
« Reply #14 on: April 10, 2019, 12:27:33 pm »
Looks like a great project! I have an HP3325B - I suspect it would use the same board. I'll have to check.
 

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Re: Cloning the HP3325A Option 002 - HV Output
« Reply #15 on: April 10, 2019, 01:01:00 pm »
Yes, the B version uses exactly the same board. It has the same part number.
 
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Re: Cloning the HP3325A Option 002 - HV Output
« Reply #16 on: April 11, 2019, 07:17:21 pm »
Are this boards for sale?
Thanks
 

Offline Neomys Sapiens

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Re: Cloning the HP3325A Option 002 - HV Output
« Reply #17 on: April 12, 2019, 12:30:28 am »
On the topic of the MAT01: even if this 'supermatch pair' is not really needed, a double transistor might be beneficial to the application. Some that are a bit easier to source: MD8002 (Mot), 2N4045, 2N2915, BFY83, SL301L, although I haven't checked their respective suitability yet.
 

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Re: Cloning the HP3325A Option 002 - HV Output
« Reply #18 on: April 12, 2019, 01:03:17 am »
Are this boards for sale?
Thanks
I'll release the gerbers and source files (if anyone else uses DipTrace) when they are finished and I'm sure I'll end up with a few spare boards when I get mine made that I could send to people who want one.
Maybe I can order a few extra sets of parts too and send them out as a kit for people to solder together themselves?


On the topic of the MAT01: even if this 'supermatch pair' is not really needed, a double transistor might be beneficial to the application. Some that are a bit easier to source: MD8002 (Mot), 2N4045, 2N2915, BFY83, SL301L, although I haven't checked their respective suitability yet.
Cool, I'll take a look at thoise suggestions and see what matches up.
Failing that, using superglue to marry a somewhat matched pair of transistors could work in a pinch. :)
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Offline VK5RC

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Re: Cloning the HP3325A Option 002 - HV Output
« Reply #19 on: April 12, 2019, 01:17:59 am »
Thanks for the post, @Terra if you are ordering boards and components and can easily add another set - I would put my hand up for one set of both parts and pcb.
Rob
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Whoah! Watch where that landed we might need it later.
 

Offline Jay_Diddy_B

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Re: Cloning the HP3325A Option 002 - HV Output
« Reply #20 on: April 12, 2019, 02:35:20 am »
Hi,

The mismatch in the input transistors Vbe, multiplied by the gain of the amplifier (x2) will appear as offset on the output voltage.

I will measure the offset voltage on my clone versus the original board.

I have been playing with the amplifier in LTspice. I believe that it can be made to be better than original design.
It is still a work in progress, but I have attached my latest LTspice model. I have removed the protection circuit for now. I will put it back at the end.





This version has a slew rate of 1600V/us.

I have made the input stage symmetrical and changed the output transistors. C2 and C3 are trimmers used to optimize the waveform.

This circuit could be used with other function generators to boost the output voltage.

I have attached the LTspice model.

Regards,

Jay_Diddy_B
 
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Re: Cloning the HP3325A Option 002 - HV Output
« Reply #21 on: April 12, 2019, 05:27:17 am »
Thanks for the post, @Terra if you are ordering boards and components and can easily add another set - I would put my hand up for one set of both parts and pcb.
Rob
VK5RC

Yeah, I'll probably make a batch of 10 or so to start.
Whichever design we end up making, I'll put together a bunch of kits. I'll wait a bit to see how Jay_Diddy_B's design goes and with his permission, I'll get something put together unless he wants to sort it out for his design.
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Re: Cloning the HP3325A Option 002 - HV Output
« Reply #22 on: April 17, 2019, 02:25:27 pm »
PCB layout V1.0 so far....  :-/O
I went 4-layer as it greatly simplified layout and I have never tried 4-layer before so I figured why not? :)

The components are laid out pretty much the same as the original, the traces are adjusted as needed.
It'll change a little when I finalize which transistors will be used, but it's mostly there.

Let me know if you see any obvious mistakes or tweaks I should do. :)
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Re: Cloning the HP3325A Option 002 - HV Output
« Reply #23 on: April 19, 2019, 01:55:00 pm »
Latest picture. :)

Lots of little tweaks and stuff to make sure stuff fits. 99% done now.
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Re: Cloning the HP3325A Option 002 - HV Output
« Reply #24 on: April 20, 2019, 01:13:54 pm »
Nice work. I haven't used LTspice before, I should learn it some day..
Is there a spice model for the MAT01GHZ for the dual transistor? I wonder how much of a difference it would make.

Apparently there is no spice model for MAT-01.  Analog has in the past recommended using the model for SSM2212 instead, which is available.

https://www.analog.com/en/license/spice-models?mediaPath=media/en/simulation-models/spice-models/SSM2212.cir&modelType=spice-models

LTSPICE does have the MAT-02 in its standard library, it may be close enough (or an alternative).
 

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Re: Cloning the HP3325A Option 002 - HV Output
« Reply #25 on: April 28, 2019, 01:40:18 pm »
Ok, time for some small updates.

I recently ordered a bunch of PCB's, so they should arrive soon.
I also just won another 3325A on Yahoo Auctions, with opt 001 (ovenised oscillator) and 002 so I can more easily compare performance between an original board and mine.


Updates to come soonish. :)
« Last Edit: April 28, 2019, 01:54:30 pm by TERRA Operative »
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Re: Cloning the HP3325A Option 002 - HV Output
« Reply #26 on: April 28, 2019, 07:24:48 pm »

Building @Jay_Diddy_B's improved board could also be interesting! 
 

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Re: Cloning the HP3325A Option 002 - HV Output
« Reply #27 on: April 29, 2019, 06:44:47 am »
Yeah, I'll have to get my hands on one when they are done to do a 3-way comparison.

Would be awesome if his could be used beyond the 1Mhz limit of the HP one, but I'm not sure if that'll require reflashing of the ROM on the 3325A motherboard or not?
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Re: Cloning the HP3325A Option 002 - HV Output
« Reply #28 on: April 29, 2019, 07:50:33 am »
It should not require a new ROM. My 3325B is happy to provide any frequency, even is Opt002 is enabled. It seems like that the only change is that id adjusts the output amplitude display, but does not limit the upper frequency.
 

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Re: Cloning the HP3325A Option 002 - HV Output
« Reply #29 on: May 03, 2019, 03:42:23 pm »
Alrighty, I got my hands on an original option 002 board.  ;D

Here are some high quality photos of the thing for those who are interested.

Interestingly, there was a shield on this one which I didn't realise was part of the upgrade. It wouldn't be very difficult to make one at all.
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Re: Cloning the HP3325A Option 002 - HV Output
« Reply #30 on: May 03, 2019, 03:43:11 pm »
Some more shots.
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Re: Cloning the HP3325A Option 002 - HV Output
« Reply #31 on: May 03, 2019, 03:43:52 pm »
And a few more, showing the shield.


Someone might find these pics useful. :)
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Re: Cloning the HP3325A Option 002 - HV Output
« Reply #32 on: May 07, 2019, 12:57:04 pm »
PCB's have finally arrived!  ;D

They are basically a 4 layer copy of the original board. Component placement is as close to the original board as possible, traces are different as needed.
Next step is to solder it together and test that it actually works........

If anyone is interested in one of these, let me know. I have 20 PCB's and I'll supply them as a full kit of parts, with all parts needed to complete one board, including parts to make interconnect wires and screws to mount it in the machine etc.
If I get an idea of who is interested, I'll be able to price up what they are worth for a kit.
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Re: Cloning the HP3325A Option 002 - HV Output
« Reply #33 on: May 16, 2019, 02:12:55 am »
Pow! Got the first one assembled.  :-/O  ;D

A few things of note so far:
You may notice a few smaller resistors in the mix, I accidentally purchased 0.25W instead of 0.6W...   :palm: No big deal, just looks weird, I'll fix that with my next Digikey order.
Also, I noticed only after I installed them that the two 10K resistors are specified as 0.1%, 0+-25 Temp Coefficient types... I used 1%, +-50 TC types.. These must be a little critical to stability, but the ones I have will be fine until the next order.
All the rest of the resistors are 1%, +-50 TC types (I can get most of the values for 3yen a piece in Akihabara so yay), which is WELL under the specs in the parts list. Most are specified at 1% 0+-100 or 5% -400/+500.


All the ceramic capacitors I used are C0G/NP0 types too, so good for performance there.


The two axial tantalums have been substituted with axial electrolytics.
For the final version, what do people think of this:
https://www.digikey.com/product-detail/en/kemet/T110B335K035AT/399-11296-ND/4552792
(Rated ESR of 4 \$\Omega\$)

Compared to this:
https://www.digikey.com/product-detail/en/nichicon/TVX1H3R3MAD/493-16279-ND/2539907
(Measured ESR of 2.6 \$\Omega\$)

It's a difference of $2.95 vs $0.55..... I think the electrolytic would be fine, no need to use the tant?


Transistors are 2N3904 and 2N3906, output drive transistors are MJE243G and MJE172G in place of MJE223 and MJE233 respectively.
- MJE223 NPN, 80V, 10MHz
- MJE243G NPN, 100V, 40MHz

- MJE233 PNP, 80V, 10MHz
- MJE172G 80V, 50MHz

Will be interesting to see how they compare at the higher frequencies...


For the dual transistor on the input (The heat sinked can to the right, I replaced the HP part 1854-0475 with two 2N3904's superglued together that I hfe and Vf matched with my ebay component tester.


And finally, I used all 1N4150 diodes (80V) in place of both the 1N4150 and 1N4148 (30V) diodes to simplify things. Diodes are cheap and I ain't penny pinching that much....


Now to wait a few days for some time to start testing. Got family arriving from overseas, so it's time to relax, do some sight-seeing and heat up the barbeque.  ;D
« Last Edit: May 16, 2019, 02:23:24 am by TERRA Operative »
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Offline Neomys Sapiens

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Re: Cloning the HP3325A Option 002 - HV Output
« Reply #34 on: May 17, 2019, 05:18:12 pm »
Pow! Got the first one assembled.  :-/O  ;D


The two axial tantalums have been substituted with axial electrolytics.
For the final version, what do people think of this:
https://www.digikey.com/product-detail/en/kemet/T110B335K035AT/399-11296-ND/4552792
(Rated ESR of 4 \$\Omega\$)

Compared to this:
https://www.digikey.com/product-detail/en/nichicon/TVX1H3R3MAD/493-16279-ND/2539907
(Measured ESR of 2.6 \$\Omega\$)

It's a difference of $2.95 vs $0.55..... I think the electrolytic would be fine, no need to use the tant?

I would use the Kemet. Being of hermetic construction, it will keep it's parameters for a long time. Those are not the failure prone Tants! Also Kemet specs are reliable and conservative.
 

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Re: Cloning the HP3325A Option 002 - HV Output
« Reply #35 on: May 18, 2019, 12:50:11 am »
Awesome, thanks.

Yeah, I thought it would be too big for the cheap boards.. :(
Ah well, it's still not tooooo expensive anyway. I wonder if there is anywhere that will do gold plating and also clear or no solder mask to match the old HP style PCB? :D

If you take a look at my boards, you'll see they are gold plated with no soldermask on the top to match the HP boards. They look more brown only due to the internal copper layers from the 4 layer construction.



I would use the Kemet. Being of hermetic construction, it will keep it's parameters for a long time. Those are not the failure prone Tants! Also Kemet specs are reliable and conservative.

Yeah, the lifetime of the tants is impressive compared to the electros. The electrolytics I used are only rated to 2000 hours or so.
What about squeezing a poly or ceramic cap in, seeing as these are only 3.3uf?
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Offline Jay_Diddy_B

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Re: Cloning the HP3325A Option 002 - HV Output
« Reply #36 on: May 18, 2019, 05:05:13 am »
Hi,

I used a tantalum bead. The capacitor has about 3.7V applied. The current is low, about 1mA peak, during square wave transitions. The current is lower with a sinewave. The value is not critical. A 4.7uF 10V (or greater) will be okay.

I used something like this:

https://www.digikey.com/product-detail/en/avx-corporation/TAP475K035SRW/478-8986-1-ND/4561852

Regards,

Jay_Diddy_B
 

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Re: Cloning the HP3325A Option 002 - HV Output
« Reply #37 on: May 28, 2019, 01:14:04 am »
Alrighty. Got it working finally.
Turns out that after a bit of head scratching, Diptrace have the Emitter and Collector pins swapped on some of their footprints, or the part I used is swapped from the normal footprint...  :rant:  The usual story....  |O

So that means I have a heap of gold plated 4-layer boards to feed the bin.  :(

Anyway, it's all figured out and ready for a new PCB order, plus I made a few tweaks to placement for clearances and stuff, just minor stuff, a nudge here and a bump there.

Here's the output shown in the pics below.
In order:
- 1MHz Sine (The device seems to attenuate above 1MHz)
- 1Mhz Square
- 100KHz Square
- Close up of the 100KHz square rising edge

Things might need to be poked a bit to reduce that overshoot? Any suggestions?
The overshoot seems to stay the same regardless of frequency setting, until it distorts like in the 1MHz image, which starts around 500KHz, where the period becomes the same width as the overshoot ripple.
(The 1MHz square wave shape is showing just a portion of the overshoot ripple, hence the distorted shape for example).

The triangle and ramp are perfect and boring, so I won't bother with pics.
« Last Edit: May 28, 2019, 01:19:09 am by TERRA Operative »
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Re: Cloning the HP3325A Option 002 - HV Output
« Reply #38 on: May 31, 2019, 02:12:24 am »
Moar updates.

It turns out that the Original HP Option 002 board I have wasn't working, but I traced it down to a faulty transistor Q8, it seemed to test ok in my ebay component tester, but it was nonfunctional enough to bring the whole thing to a grinding halt. Replacing it got the board working perfectly.

So, seeing as it works fine with no overshoot, and I need to order another revision of PCB anyway, I ended up just copying the PCB layout with a few tiny tweaks here and there (stuff like neatening up things, 45degree corners, etc).
The added benefit of no longer using a 4 layer board is that PCB's will be cheaper. :)
I am thinking that the large ground and supply planes were adding capacitance and causing ringing, maybe. Thoughts?
I could play with pulling the ground planes back a bit, but I figured 'why bother' when I am holding a working design to copy in my hand....

Anyway, the linked images are the new PCB design, and the output from the repaired original Option 002 board.


Once I get this set of PCB's back and the thing tested, I'll be able to start getting some kits made up for those who are interested.
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Re: Cloning the HP3325A Option 002 - HV Output
« Reply #39 on: June 29, 2019, 12:31:54 pm »
New PCB's arrived!

I ended up with two batches, first one they ignored the keepout on the top solder mask, so I have a set of 10 boards with and without top solder mask.
Since the original HP part has no top solder mask, I wanted the same to make it look the same.

Original on the top (already had the electrolytics replaced) and new on the bottom. The traces are a 90% match to the original, and all modern parts are used and substituted and the passives have better specs than the original.

Next step, start testing this to make sure my component values and substitutions all work.
« Last Edit: June 29, 2019, 12:34:06 pm by TERRA Operative »
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Offline VK5RC

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Re: Cloning the HP3325A Option 002 - HV Output
« Reply #40 on: June 29, 2019, 01:10:15 pm »
That is looking lovely, when you are happy, I will put my hand up for one.
Rob
VK5RC
Whoah! Watch where that landed we might need it later.
 

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Re: Cloning the HP3325A Option 002 - HV Output
« Reply #41 on: May 16, 2020, 06:03:47 am »
I'm late but I would also be interested in a PCB only board or whole kit, thanks
 

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Re: Cloning the HP3325A Option 002 - HV Output
« Reply #42 on: May 16, 2020, 06:58:43 am »
No worries, I'm sorting out the kits etc at the moment for a big run.

It will be delayed for a while, as Japan Post has basically shut down international shipping due to the corona virus, but as soon as restrictions are lifted, I'll get things organised.
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Re: Cloning the HP3325A Option 002 - HV Output
« Reply #43 on: May 17, 2020, 08:36:34 am »
With reference to the dual input NPN (1854-0475), resulting obsolete, expensive, nowhere to be found, I would propose to focus on AS194, improved device of the AS394, components produced by a company from Riga in Latvia, they seem to be devices seriously built with vision of datasheets. Regards, Franco
 

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Re: Cloning the HP3325A Option 002 - HV Output
« Reply #44 on: May 17, 2020, 09:08:51 am »
I am still interested, but no rush.
Thanks, Rob
Whoah! Watch where that landed we might need it later.
 

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Re: Cloning the HP3325A Option 002 - HV Output
« Reply #45 on: May 17, 2020, 10:00:02 am »
Quoting some 2015 post on group.io:
Quote
pianovt
7/21/15   #70601 

It looks like Bob saved the day! Just in case someone finds this thread in the future while searching for a replacement, here is what I found for the 1854-0475 dual NPN:

Vceo >40V
NF < 3dB
Ft > 15 MHz
Cob < 3pF
hfe > 200 at 100uA
hfe match better than 0.8
Vbe match better than 10mV at 100uA Ic and 5V Vce
Pd 750mW max. at Ta

Vladan


Cob is way to high on LM194 based clone in general. It is not specified on the AS version.
They are generally slow too, as the Hp one so with high Vce/Ic polarisation and high Pd : The Hp one even rated at 750mW is mounted with a dissipator.

 

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Re: Cloning the HP3325A Option 002 - HV Output
« Reply #46 on: May 17, 2020, 12:34:10 pm »
2N2920AHR seems to be a good replacement. Active product but difficult to find (ST space qualified portfolio).
Microsemi 2N2920(L) is only 350mw max an very expensive.

2915A/2920A from Solid Sate Inc/Texas Instruments, 2N2920 from Thoshiba 2920A from central semi should be good but hard to find or obsolete.

Why not simply MAT01 ? Available anywhere at not foolish price. Ok perhaps a little but expensive for the HV option, but as a general 1854-0475 replacement ?
2920A From Solid State cost only 2$ less than a MAT01GHZ (~17 vs ~19)
« Last Edit: May 17, 2020, 12:57:11 pm by Tazz »
 

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Re: Cloning the HP3325A Option 002 - HV Output
« Reply #47 on: May 18, 2020, 03:53:55 am »
2N2920AHR seems to be a good replacement. Active product but difficult to find (ST space qualified portfolio).
Microsemi 2N2920(L) is only 350mw max an very expensive.

2915A/2920A from Solid Sate Inc/Texas Instruments, 2N2920 from Thoshiba 2920A from central semi should be good but hard to find or obsolete.

Why not simply MAT01 ? Available anywhere at not foolish price. Ok perhaps a little but expensive for the HV option, but as a general 1854-0475 replacement ?
2920A From Solid State cost only 2$ less than a MAT01GHZ (~17 vs ~19)

The circuit will work quite well with two ordinary MPS8099 transistors glued together.

When I built mine it worked fine, without selecting or matching the transistors.

In simulation a miss-match of HFE one transistor 250 and the other 300 results in about 20mV of offset on the output.

I would try ordinary transistors before going chasing after special parts.

Total Power dissipation for both transistors is around 180mW.

The HV Option 002 amplifier schematic is similar to the normal output. Look at the schematics in the service manual. I am guessing the dual transistor was copied from there.  :-//

Regards,
Jay_Diddy_B

« Last Edit: May 18, 2020, 03:55:53 am by Jay_Diddy_B »
 
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Offline Tazz

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Re: Cloning the HP3325A Option 002 - HV Output
« Reply #48 on: May 18, 2020, 06:09:48 am »
Yes going back in the thread show me that I should have reread all first instead of going through all reference catalogs ...  :-DD
« Last Edit: May 18, 2020, 09:19:14 am by Tazz »
 

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Re: Cloning the HP3325A Option 002 - HV Output
« Reply #49 on: May 18, 2020, 01:28:20 pm »
Tazz,

You can buy a *lot* of general purpose transistors for the price of the MAT01 or equivalent. You may even have some  ;D

The transistor in the input stage have 45V VCE. (+/- 30V minus the  15V Zener)

So you need 60V parts.

I used 80V parts.

Jay_Diddy_B
 

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Re: Cloning the HP3325A Option 002 - HV Output
« Reply #50 on: August 04, 2020, 06:22:09 pm »
I would always be interested in the clone of the HVO option of the 3324A, I ask the current status of this project by the interested parties seen in this forum. Greetings Franco
 

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Re: Cloning the HP3325A Option 002 - HV Output
« Reply #51 on: August 05, 2020, 02:36:29 am »
Outbound international shipping from Japan is still shut down, still waiting for things to start moving again. Will make more updates when I have new news.
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Re: Cloning the HP3325A Option 002 - HV Output
« Reply #52 on: August 05, 2020, 02:51:28 am »
I would always be interested in the clone of the HVO option of the 3324A, I ask the current status of this project by the interested parties seen in this forum. Greetings Franco

Hi,

I haven't seen the HV Option for the HP3324A. Is it the same as the HV option for the HP3325A?

Regards,
Jay_Diddy_B
 

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Re: Cloning the HP3325A Option 002 - HV Output
« Reply #53 on: September 20, 2020, 07:45:06 pm »
I wired the proposed improved circuit on breadboard, redesigned with kicad, but it doesn't work, Q3-Q9-Q13 warm up slightly, in the absence of signal the output has no important offset. is there any error in the wiring?[attachurl=1]
 

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Re: Cloning the HP3325A Option 002 - HV Output
« Reply #54 on: September 23, 2020, 08:40:22 am »
Did you end up finding the problem?

It simulates properly with ltspice and is quite tolerant to model variations for the various transistors.
Given that you have "breadboarded" the circuit it is most likely an issue with your physical wiring.

I've just finished a quick laying out a surface mount version of that circuit and currently verifying transistor selections.
I'm doing it on a 4 layer pcb for no other reason than to check out JLPCB's 4 layer service

P.S.
Hope you don't mind Jay :)

 

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Re: Cloning the HP3325A Option 002 - HV Output
« Reply #55 on: September 23, 2020, 01:44:06 pm »
Hi,

I see that you have copied the circuit from this post:

https://www.eevblog.com/forum/testgear/cloning-the-hp3325a-option-002-hv-output/msg2337558/#msg2337558



It is still a work in progress, but I have attached my latest LTspice model. I have removed the protection circuit for now. I will put it back at the end.

I have never taken this beyond the LTspice model.



I used 2n3904 and 2n3906 transistors in the LTspice model, these are 40V transistors. I can do this in SPICE because SPICE doesn't model the breakdown voltage.

Q4, Q5, Q11 and Q12 should be 80V transistors.

So building this circuit is risky.

Protection

I have highlighted the parts that need to be added to implement protection for the output devices.

[attachimg=1]


4 Layer Board

Terra Operative used the original HP schematic and built it on a 4-layer board. It did not work as well the original 2 layer design. This is documented in this message:

https://www.eevblog.com/forum/testgear/cloning-the-hp3325a-option-002-hv-output/msg2450364/#msg2450364

I think there may be similar issues building the amplifier I designed on a 4-layer board.

Regards,
Jay_Diddy_B

 
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Offline AlfBaz

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Re: Cloning the HP3325A Option 002 - HV Output
« Reply #56 on: September 23, 2020, 03:23:01 pm »
Hi Jay, thank you for the clarification.

I mentioned that I was in the process of "verifying transistor selection".

In actual fact all I have done is drawn up the schematic with generic components and pushed their generic foot prints to the PCB, followed by a quick route.
The only thing that's complete is the size of the board and the position of the BNC's to suit the Hammond case I've chosen
 
I had noted you removed the protection circuits but decided to go without to simply see how it performed compared to the simulation and to the data you and Terra Operative collected.
I'll just have to be extra careful when testing.

Thanks for pointing out the 4 layer issue, I had missed that.
I originally went 2 layer but didn't save that version when I changed to 4 layers. Just some extra vias really so no big deal to change it back.
I have a different stack up so I might still go 4 layer just to see what happens as all my signals are on the top layer followed by Vcc, Vee and finally ground on the bottom.
I'll order both the 4 and 2 layer boards at the same time and enough components to do both. I like making mistakes, it's how I learn :)

LTspice shows current draw from the rails as less than 100mA so I may be able to use smaller regulators than the ones currently used for the final board. I'll leave it as is and test on the actual circuit first
 

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Re: Cloning the HP3325A Option 002 - HV Output
« Reply #57 on: September 23, 2020, 03:30:38 pm »

I'm not sure I totally understand why the 4 layer board is a problem -  does it introduce extra capacitance that rounds the edges of the signal, or something like that?
 

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Re: Cloning the HP3325A Option 002 - HV Output
« Reply #58 on: September 23, 2020, 03:48:49 pm »
I believe the problem was overshoot as shown in the post just before the one linked by Jay_Diddy_B. There may be some signals coupling via the planes :-//
 
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Re: Cloning the HP3325A Option 002 - HV Output
« Reply #59 on: September 23, 2020, 05:04:40 pm »

P.S.
Hope you don't mind Jay :)

I don't mind at all. I encourage it.



AlfBaz,

I would add some copper to the collector connections on the output transistors Q7 and Q8. There is no concern with capacitance to the ground plane, because these are essentially at dc potentials. You look at the LTspice model for the dissipations.

I suspect that the issue with the four layer board is capacitance to the ground plane. This is a high speed circuit running at relatively small currents.

All we really know is that the original circuit, my layout and Terra Operative's second layout all work better than the Terra Operative's 4-layer version.

Regards,
Jay_Diddy_B
 
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Re: Cloning the HP3325A Option 002 - HV Output
« Reply #60 on: September 23, 2020, 07:44:53 pm »
After seeing the smd PCB I threw the breadboard in the trash, congratulations to the designer, I wait for developments.
 
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Re: Cloning the HP3325A Option 002 - HV Output
« Reply #61 on: October 07, 2020, 05:00:37 pm »
Works well I think. :)
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Re: Cloning the HP3325A Option 002 - HV Output
« Reply #62 on: October 07, 2020, 05:16:01 pm »
Hi TERRA Operative,

It looks great!

It looks and works just like the original.

Regards,
Jay_Diddy_B
 
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Re: Cloning the HP3325A Option 002 - HV Output
« Reply #63 on: October 10, 2020, 05:28:05 pm »
Made a video about my Option 002 PCB, some may find it a little less than dead boring. :D



Link to all the files, BOM, gerbers etc:
https://drive.google.com/drive/folders/1l8sT5sR7wLVCqZOov9T9yXTmKLvo_4Qv
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